/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
/// History::clear() clears the history tables
void History::clear() {
- memset(history, 0, 2 * 8 * 64 * sizeof(int));
- memset(successCount, 0, 2 * 8 * 64 * sizeof(int));
- memset(failureCount, 0, 2 * 8 * 64 * sizeof(int));
+ memset(history, 0, 16 * 64 * sizeof(int));
+ memset(maxStaticValueDelta, 0, 16 * 64 * sizeof(int));
}
assert(square_is_ok(to));
history[p][to] += int(d) * int(d);
- successCount[p][to]++;
// Prevent history overflow
if (history[p][to] >= HistoryMax)
for (int i = 0; i < 16; i++)
for (int j = 0; j < 64; j++)
- history[i][j] /= 4;
+ history[i][j] /= 2;
}
/// called for each non-capturing move which failed to produce a beta cutoff
/// at a node where a beta cutoff was finally found.
-void History::failure(Piece p, Square to) {
+void History::failure(Piece p, Square to, Depth d) {
assert(piece_is_ok(p));
assert(square_is_ok(to));
- failureCount[p][to]++;
-}
-
-
-/// History::move_ordering_score() returns an integer value used to order the
-/// non-capturing moves in the MovePicker class.
-
-int History::move_ordering_score(Piece p, Square to) const {
-
- assert(piece_is_ok(p));
- assert(square_is_ok(to));
+ history[p][to] -= int(d) * int(d);
- return history[p][to];
+ // Prevent history underflow
+ if (history[p][to] <= -HistoryMax)
+ for (int i = 0; i < 16; i++)
+ for (int j = 0; j < 64; j++)
+ history[i][j] /= 2;
}
-/// History::ok_to_prune() decides whether a move has been sufficiently
-/// unsuccessful that it makes sense to prune it entirely.
+/// History::set_gain() and History::gain() store and retrieve the
+/// gain of a move given the delta of the static position evaluations
+/// before and after the move.
-bool History::ok_to_prune(Piece p, Square to, Depth d) const {
-
- assert(piece_is_ok(p));
- assert(square_is_ok(to));
+void History::set_gain(Piece p, Square to, Value delta) {
- return (int(d) * successCount[p][to] < failureCount[p][to]);
+ if (delta >= maxStaticValueDelta[p][to])
+ maxStaticValueDelta[p][to] = delta;
+ else
+ maxStaticValueDelta[p][to]--;
}